Role of lipid modifications in targeting proteins to detergent-resistant membrane rafts - Many raft proteins are acylated, while few are prenylated
Role of lipid modifications in targeting proteins to detergent-resistant membrane rafts - Many raft proteins are acylated, while few are prenylated
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DOI：
10.1074/jbc.274.6.3910
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发表时间：
1999-02-05
影响因子：
4.8
通讯作者：
Brown, DA
中科院分区：
文献类型：
--
作者：
Melkonian, KA;Ostermeyer, AG;Brown, DA
鞘脂和富含胆固醇的Triton x -100不溶性膜碎片（耐洗涤剂膜，DRMs）含有类似于液体有序相的脂质，可以从哺乳动物细胞中分离出来，并且可能以离散结构域或筏形式存在于完整的膜中。我们假设对这种有序的脂质环境具有高亲和力的蛋白质可能是筏的目标。饱和酰基链应该倾向于一个延伸的构象，这将很好地适应筏。相反，戊烯基与酰基链一样疏水，但具有支链和庞大的结构，应排除在筏中。在这里，我们发现Madin-Darby犬肾细胞DRMs中至少一半的蛋白质（除了细胞骨架污染物）可以用[H-3]棕榈酸酯标记。流感血凝素与DRMs的关联需要其所有三个棕榈酰化的Cys残基。通过[H-3]甲羟戊酸标记或印迹Rap1、Rab5、G（β）或Ras检测到的Prenylated蛋白被排除在DRMs之外。Rab5和H-Ras各自含有不止一个脂质基团，这表明疏水性本身不能将多个脂质修饰蛋白靶向DRMs。将共价连接的饱和酰基链划分为液体有序相结构域可能是将蛋白质靶向drm的重要机制。
Sphingolipid and cholesterol-rich Triton X-100-insoluble membrane fragments (detergent-resistant membranes, DRMs) containing lipids in a state similar to the liquid-ordered phase can be isolated from mammalian cells, and probably exist as discrete domains or rafts in intact membranes. We postulated that proteins with a high affinity for such an ordered lipid environment might be targeted to rafts. Saturated acyl chains should prefer an extended conformation that would fit well in rafts. In contrast, prenyl groups, which are as hydrophobic as acyl chains but have a branched and bulky structure, should be excluded from rafts. Here, we showed that at least half of the proteins in Madin-Darby canine kidney cell DRMs (other than cytoskeletal contaminants) could be labeled with [H-3]palmitate. Association of influenza hemagglutinin with DRMs required all three of its palmitoylated Cys residues. Prenylated proteins, detected by [H-3]mevalonate labeling or by blotting for Rap1, Rab5, G(beta), or Ras, were excluded from DRMs. Rab5 and H-Ras each contain more than one lipid group, showing that hydrophobicity alone does not target multiply lipid-modified proteins to DRMs. Partitioning of covalently linked saturated acyl chains into liquid-ordered phase domains is likely to be an important mechanism for targeting proteins to DRMs.